Ryan’s leetcode Blog

Description: Count the number of prime numbers less than a non-negative number,  n . 厄拉多塞筛法(Sieve of Eeatosthese): 从第一个质数开始 把所有他的倍数都去掉,...

Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: 1 -> A 2 -> B ...

Given  n  points on a 2D plane, find the maximum number of points that lie on the same straight line. 给一个2d的平面, 所给的数据结构point代表一个点, 让找一条点最多的...

Validate if a given string is numeric. Some examples: "0"  =>  true " 0.1 "  =>  true "abc"  =>  ...

Implement  int sqrt(int x) . 注意这道题是返回int 的平方根 所以: sqrt(3) = 1 sqrt(4) = 2 sqrt(5) = 2 sqrt(10) = 3 用二分法来判定 逐步找到平方根, 但是要注意的是只要符合 m...

Given two binary strings, return their sum (also a binary string). For example, a =  "11" b =  "1" Return  "1...

Given a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significa...

Given two numbers represented as strings, return multiplication of the numbers as a string. Note: The numbers can be arbitrarily large an...

Reverse digits of an integer. Example1:  x = 123, return 321 Example2:  x = -123, return -321 "越是简单的题目越要注意细节，一般来说整数的处理问题要注意的有两点，一...

The set  [1,2,3,…, n ]  contains a total of  n ! unique permutations. By listing and labeling all of the permutations in order, We get t...